Monday, November 13, 2006

No-Till versus Conventional-Till: Major Soil Hydrologic Components.

Dinku Endale, Harry Schomberg, and Michael Jenkins. USDA-ARS, 1420 Experiment Stn. Rd., Watkinsville, GA 30677

Adoption of no-till has increased in recent years but quantitative data differentiating soil hydrology parameters between no-till and conventional tillage methods are needed on site-specific basis to help growers make tillage choices that are knowledge-based.  We quantified differences in runoff, drainage and soil water recharge between no-till (NT) and conventional tillage (CT) in a Cecil soil under irrigation. The study was carried out on twelve 10-m by 30-m plots on June 4 and 5, 2002 at the USDA-ARS J. Phil Campbell Sr. Natural Resource Conservation Center. Half the plots had been under NT and the other half under CT since 1991.  Runoff and drainage were significantly different among the two tillage types for each of the two irrigation events and the combined two day event. In the first event on June 4, 55 mm of irrigation was applied in six hours. A 13-mm rain fell during the night. No runoff was recorded but drainage was 38% more from NT. About 44 mm of the applied water was retained in the soil. In the second event on June 5, about 67 mm of irrigation was applied in seven hours and a 12-mm rain fell during the night.  The CT plots had 4 times more runoff, while the NT plots had twice more drainage. Very little additional water was retained in the soil. Over the two days, 89% more drainage occurred from NT while runoff was four times more from CT.  The net soil water change estimated by water balance calculations and soil water measurement varied within 10%. The results confirm findings in previous research that no-till enhances infiltration in Cecil soils. Farmers and regional water resource planners ought to actively utilize this information for better management of water resources and cropping.